BlackBerry Passport reboot frequently after the error bb10-0015

One problem perplexed me of my BlackBerry Passport more then 6 months, my device was rebooting frequently after the error bb10-0015 happened 6 months ago, I have follow the instruction from internet how to reinstall the OS and the error has resolved, my device can work finally, but another problem comes out, my device was frequently rebooting itself when I am using the device or even it was not in use and just put it on my table overnight, I tried to sweep away the device, trying to install the new version of OS, using the updated auto loader to sweep the device or else, it seems no help on the rebooting issue, I also tried to install only the apps only for BB and didn't install any apps from Android, it is no help also, my device already reboot itself without any advance notification, it makes me perplexing on the device but really want to find a way to resolve the rebooting issue, so that anyone can provide me any solution or method step by step to resolve the issue, thanks for all you guys. Hence my device brought in UK, but I tried to contact BlackBerry UK for how to repair my device, after they call me and I follow the instruction from them to step by step restore my device, it doesn't help and tried to contact them again, no one feedback me anymore, it seems I need to find the way by myself. 10.3.3.2031 is the currently OS versionof my device.